You can upload it already. Any member with a validated account can upload to the Gallery and Downloads sections. It'll be hidden until approved by a staff member, but anyone can do it. Check your PM.

And yes, Tiberium is now definitely the best-documented of the canceled C&C titles. In fact we might want to consider snooping around and contacting the artists to see if they have even more stuff that isn't under NDA while they still might have it (before they delete it or it gets lost to time like the older games).